The diabetes-cure aspect of the surgery seems to be NOT entirely dependent on either weight loss or the post-op eating regimen. Of course these two things have their positive impact: people who have the stomach-banding (lap band) without re-routing the intestines, experience gradual improvenment in diabetes, but only concurrent with massive weight loss. In contrast, it was found that people who had the gastric bypass lost all their type two diabetes symptoms in a matter of days after the operation, LONG before they lost weight.
So an Italian surgeon experimented with diabetic mice and surgically restructured their intestine to bypass their duodenum. Immediately these mice lost the diabetes symptoms. Then he reattached the intestines so that the same type and amount of post-op food would, once again, go through the duodenum. Once again the mice displayed the diabetes symptoms. He concluded that the cure for diabetes may be a surgical one.
It's not entirely understood why, but the most recent research indicates that the ultimate cause of Type 2 Diabetes (for most) may be an abnormality of the upper intestine.
Happy Mother’s Day, Mrs. Don-o.